Weekly missing dose (“6/7” SSU Protocol): A rational approach in warfarin use

Sina Owlia


Warfarin is still used as a standard drug for long term oral anticoagulation. We hypothesized that chronic warfarin use six days a week (“6/7” SSU protocol) is a safe and effective method in order to minimize the burden of frequent blood testing. Our unpublished data indicated that weekly missing dose of warfarin a day per week could attain an ideal therapeutic goal with a need to less frequent blood samplings without the risk of warfarin toxicity (bleeding) or significant drop in therapeutic serum level. Our rationale was rather a high half-life of warfarin (20-60 hours) with more than 97% protein bounding. So, disruption of daily oral prescription of warfarin by off-days (a day each week) can effectively halt the risk of bleeding without considerable impact on its anticoagulation effects. We hypothesized that due to unappreciated long elimination half-life, this mode of dosing (six days a week) could be more justified than the continuous daily oral prescription. This fact has been experienced for years regarding practice with digoxin (with 36-48 hours half-life). Similarly this concept could be true for every drug with “more than a day” half-life like warfarin.


Warfarin, anticoagulation, weekly dose, “6/7” SSU protocol

Full Text:



Montiel-Manzano G, de la Pena-Diaz A, Majluf-Cruz A, et al. National evaluation of the diagnosis of activated protein C resistance. Rev Invest Clin 55:358-369, 2003.

Linhardt, R., Heparin: an important drug enters its seventh decade. Chemist Indust 2:45-50, 1991.

Nelson-Piercy C. Hazards of heparin: allergy, heparin-induced thrombocytopenia and osteoporosis. Baillieres Clin Obstet Gynaecol 11: 489-509, 1997.

Rezaieyazdi Z, et al. Reduced bone density in patients on long-term warfarin. Int J Rheum Dis 12:130-135, 2009.

Takahashi H, Echizen H. Pharmacogenetics of warfarin elimination and its clinical implications. Clin Pharmacokinet 40:587-603, 2001.

Osinbowale O, Al Malki M, Schade A, Bartholomew

JR. An algorithm for managing warfarin resistance. Cleve Clin J Med 76:724-730, 2009.

Stewart S, Murphy NF, Walker A, McGuire A, McMurray JJ. Cost of an emerging epidemic: an economic analysis of atrial fibrillation in the UK. Heart 90:286-292, 2004.

Harper P, Monahan K, Baker B. Warfarin induction at 5 mg daily is safe with a low risk of anticoagulant overdose: results of an audit of patients with deep vein thrombosis commencing warfarin. Intern Med J 35:717-720, 2005.

Pink J, Pirmohamed M, Lane S, Hughes DA. Cost-effectiveness of pharmacogene-tics-guided warfarin therapy vs. alternative anticoagulation in atrial fibrillation. Clin Pharmacol Ther 95:199-207, 2014.

Jaffer A, Bragg L. Practical tips for warfarin dosing and monitoring. Cleve Clin J Med 70:361-371, 2003.

Palareti G, Legnani C. Warfarin withdrawal. Pharmacokinetic-pharmacodynamic considerations. Clin Pharmacokinet 30:300-313, 1996.

Ahmed A, Waagstein F. Low-dose digoxin and reducti on in mortality and morbidity in heart failure. Int J Cardiol 136:91-92, 2009.


  • There are currently no refbacks.


Best Quality Medical Supplies is a registered company in Untied States specializing in sales of medical equipment and supplies. We are a distributor for hospitals, doctor offices, medical clinics, nursing schools, and nursing homes within the United States. We also provide services for overseas clients. Click here for details and orders .

The most affordable web hosting service. Click here for details and orders.